Without Steve Jobs at the helm, Apple has been widely criticized for incremental innovation. Critics charge that the firm isn’t breaking new ground the way it once did: the iPhone 5 and iPad Mini were just incremental improvements. To use Clay Christensen’s vernacular, they were sustaining, not disruptive changes. Everyone’s got high hopes for Apple’s forthcoming smart watch, but is it more than just a fashion accessory?

One earmark of the disruptive change is that people don’t know they want it yet—the Mini-van and the Walkman are widely cited examples. So it was for the iPhone and the tablet (which, it should be remembered, followed Newton’s spectacular failure.) If it is to regain its disruptive-innovator mojo, Apple needs to give people something else they didn’t know they wanted.

If I were Tim Cook, I’d be looking for a market that is huge; ripe for disruption; and noble. I’d find one that fits both Apple’s brand ambitions and stock-market enthusiasm.

I’d be building a prosthetic brain for the elderly.

This is a great example of disruptive innovation, and something that, if successful, will look obvious in hindsight. But getting there won’t be easy.

Old age is big business

We’re all living longer.

That means the market for products targeted at the elderly is growing, too. The gap between what social security and pensions can pay, and what we need, is frightening and growing fast. Today’s workers are paying for their parents’ retirements, and saving little for their own.

If you keep someone ambulatory, and living at home, you not only improve their dignity and quality of life, you also reduce their costs. Even for the very ill, home care costs roughly 33% of long-term bed care and 5% of hospital care in Canada. In the US, the difference is even more striking. Chronic care costs big bucks, along with nursing, diagnostics, so on. It’s even better if you can delay the need for constant care somehow.

And today’s working adults, which Pew Research calls the Sandwich Generation, are stuck between a youth that they continue to support after school, and parents living longer.

In recent months, I’ve spent a lot of time looking at what it means to get older. Not just because my own time marches inexorably onwards, but because family and friends are reaching that age where hands shake and eyes don’t focus, where things—and appointments—go missed.

As Boomers enter their sunset years, their Sandwich Generation children—awash in a sea of technology—will want them to get connected. We’ll believe that tech can keep an eye on them, keep them engaged, and help them with everything from navigating public transit, to remembering to take pills, to staying in contact with friends and family as they become less ambulatory. There’ll be no need to push a button to say you’ve fallen and can’t get up; technology will push it for you.

Unfortunately, my research into applications to help a group such as the sight-impaired read shows a fragmented set tools, inconsistent standards, and good intentions (some resources here.) Many designers treat assistive devices as an afterthought, and most sites and apps are unusable if you don’t have thumbs, eyes, and ears. That has to change.

Room for innovation and disruption

In 2009, women over 55 were the fastest-growing segment on Facebook. Older generations are keen to join the online world. But the technology they need isn’t the technology we’re making.

Consider, for example, someone with failing eyesight. On the surface, an iPad looks promising: Siri can find search results with voice commands. And the device’s assistive functions let it speak text to you in an understandable voice.

Unfortunately, using these doesn’t work as well as you might hope. Shaking hands can’t select the text precisely enough to trigger the speech function, making it largely useless.

(Here’s a post from 9to5mac explaining how it works.)

Similarly, Siri’s results come from a wide range of sources, which makes it harder to find an authoritative answer that’s delivered succinctly. What’s needed is a smart bias towards a few useful ones. Bigger fonts are not the answer; better anticipation is. Technology needs to learn, and to change its role to suit the user. As the user becomes less certain, the device needs to make more decisions. Contact lists shrink; guiding the user to the single best answer happens more.

What’s needed is more than a redesign—it’s a rethinking. The problems are hard. They span design, machine learning, cognitive science, and medicine. Here are three functions that would be incredibly useful to someone with diminished senses, all of which are real products today:

• A smart, phone-assisted hearing aid that can respond to ambient sound levels and understand when you’re listening to music and when you’re in a conversation.
• A device that scans words in your field of view, then reads them to you carefully and clearly.
• An always-on camera that reminds you of who someone is when you see their face.

Ultimately, these are the kinds of good, chewy problems on which intellectual property and barriers to entry are erected. Apple, Google, and Microsoft, armed with Siri, Now, and Cortana, are perhaps the only three companies that could pull this off as a single product launch. But whoever gets it right will eventually redefine computing for everyone, not just the aging.

Usage is diagnostics

Portable, digital glucose monitors change the lives of diabetics. That alone is a huge industry, and continuous glucose monitoring alone is projected to be a $500M industry by 2020. A mobile, connected device can become the hub for a personal-area-network of devices and sensors, and devices like Apple’s much-speculated (and pretty much confirmed) watch, along with wristfulls of Pebbles, Up! Bands, and Nike Fuel Bands, are recording our lives a movement at a time.

Portable devices also streamline diagnostic costs. Already forward-thinking insurance companies like Oscar offer mobile apps to talk to physicians, reducing the burden on doctors. Having lost the ability to refuse pre-existing conditions in the face of Obamacare, insurance companies need to restore their margins in other ways. From scheduling appointments, to sharing patient records with trusted family members, to at-home virtual consultations, to consumer DNA testing, digital optimization of healthcare is coming.

The ways we’re finding to measure health from our pockets are astonishing. Take, for example, Asthmapolis (now Propeller Health), which attached GPS trackers to asthma inhalers to build a map of respiratory triggers and correlate it with city pollution.

There’s plenty more in the works, driven by the Quantified Self movement and backed by early adopters on Kickstarter, measuring everything from heart rate to blood pressure to blood sugar to body temperature to blood oxygen content to melanomas.

But it’s the inherent forms of sensing that, for me, hold the most promise. In the interactive age, when you watch something, it watches you back. Consider that each time we unlock a phone, we’re performing a tiny cognitive test. The data exhaust of our everyday lives is grist for the analytical mill of healthcare.

• If our fingers waver, or we can’t remember the numbers properly, might it be a sign of early-onset dementia?
• If we press the back button more often when writing, are we making more mistakes?
• Does the angle of our phone, or the amount of eye movement during a video call, tell us something important about our health?
• Does less smiling or facial slackness indicate a minor stroke?
• Does the sound of a stream of urine correlate with prostate enlargement?
• Can we measure gait, and time of day, and infer health?
• Does the frequency of a toilet flushing, or the duration spent sitting still before that flush, predict other ailments?

These, and a million other traits, multiplied by the power of big data into a Petabyte corpus on aging, would be a goldmine for physicians and researchers. And they’d make smart devices smarter with each step, flush, and tap.

A huge market

On a more cynical—but necessary—front, the product would sell. It might sound callous to talk about such high-minded ambitions in terms of dollars, but if this kind of device is to work, it needs a million users, not only to fund its development, but also to crowdsource metrics and data from which to form a baseline. It needs some good old-fashioned greed.

To today’s busy fifty-something, parents are, as the Spirit of the West puts it, “close enough to make the effort; far enough to make excuses.” Guilt alone would make this the top holiday item. Peer pressure—from house to house in retirement communities, from schoolyard to schoolyard with word of mouth—would do the rest. It would catch on like wildfire, more so because the spending would be justified, promising significant savings from letting someone live at home longer, and avoiding acute, debilitating medical treatment by anticipating problems.

I know I’d want a device like this in my later years, partly to ease the burden on my family and partly to preserve my dignity and extend the time I can contribute to the species.

In countries where healthcare is a social benefit, such devices might even get government support. Insurance companies would leap at the opportunity to save money and anticipate problems, and to better optimize scarce resources based on patient conditions. What’s more, telephone companies crave new markets, and the elderly and sick are an untapped opportunity for them.

Bringing this to market

You can’t just launch a product like this from nothing. Disruptive innovation requires baby steps: Netflix and postal DVDs; Twitter and SMS; Tesla and a sports car. Apple’s success today as a phone manufacturer owes as much to the App Store and the original iPod as it does to savvy marketing with AT&T or the availability of good broadband.

If I were Apple, my baby step would probably be something cool that’s good at sensing the world around the user, and get a million people using it so you can build useful baselines. And I’d probably include a rich set of developer tools to get things rolling and try to consolidate the patchwork of tools and protocols out there today. Then I’d use my market dominance to get the FDA on board, positioning it as the salvation of healthcare worldwide.

I might even launch a watch.

If Apple doesn’t launch this product, Google certainly will. It has the necessary building blocks, from mobile OS to machine learning. Google’s only taken the covers off of half its futuristic Google X projects, and they’ve been startling and hugely disruptive so far. And Microsoft—if you’re listening, this is how you can be cool again. Windows Mobile was awesome, but three years too late; don’t miss this market too.

Finally—it’s a great story

If Apple were to launch such a product—part videoconferencing tool, part PDA, part diagnostic, part cognitive assistant, part hearing aid—it would change what it means to grow old. If anyone can build a prosthetic brain for aging humans, and make it cool, it’s them.

Imagine Tim Cook taking the stage, framing a gigantic problem, painting the solution in broad strokes, not a dry eye in the house.

Apple will be changing the world for us. We’ll believe in them again.

And we’ll realize, it’s what Steve would have done.